Vibration device



June 11, 1929. A. A. CLOKEY VIBRATION DEVICE Filed Dec. 29, 1923 Patented June 11, 1929.

UNITED STATES PATENT OFFICE.

ALLISON A. CLOKEY, OF RUTHERFORD, NEW JERSEY, ASSIGNOB TO WESTERN REC- TRIO 001mm, rizcoaroaa'rnn, or YORK.

NEW YORK, N. I, A CORPORATION 01 NEW VIBRATION DEVICE.

ilpplication fled- December 29,1828. Serial No. 683,304.

This invention relates in general to vibrating devices and'more particularly to a'me'ans for controlling the rate of vibration of electrically driven tuning forks.

In various telegraph systems such, for example, as the well known multiplex systems, it is necessary for satisfactory operation to maintainthe apparatus at the separated stations in very close synchronism. A proximate synchronism is ordinarily obtained by driving the mechanism at the respective stations by means of an impulse motor of the La Cour type, the impulses for which are obtained from carefully adjusted tuning forks 18 arranged to be electrically driven. However, irrespective of the'care with which such forks are adjusted, they do not operate in sufiiciently close synchronism to provide satisfactory results and it becomes necessary to provlde at one of the stations, means for automatically correcting the rate of vibration of the fork at that station to conform to the rate of vibration of the fork at the controlling sta-.' tion. In order to obtain sufliciently close adjustment of'thefork to permit satisfacrycorrection, it has been a common practice to provide a pair of weights which are slidable along the fork tines by means of an adjusting screw, thus varying the frequency of vibration of the fork. Such an arrangement, however, has been found to be unsatisfactory for use with printing telegraph apparatus operating at high speeds on submarine cables, since the rate of vibration of the fork varies a small amount which makes it'practically impossible to obtain sufliciently close correction of the controlled .fork when 0 crating under such, rigid conditionsand athigh speeds. This variation was found to be due. to a slight change in the position of the wei hts as aresult ofthe vibration of the fork, t us causing a corres onding change in the rate of vibration. 1 gince it is oftenr' uired to make small ad- 7 j ustments on the fdi'k while it is in operation,

it has not been found satisfactory to remedy this condition by 100 ng the weights in position.

The object of the present invention is to provide a frequency adjusting means for vi-' 60 brating devices, such as electrically driven tuning forks, which will not chan e in ad justment, and one whereby the for may be .and 12 located on opposite sides 0 quickly and accurately adjusted while in operation.

stood by reference to the accompanying draw- I ing in which there is disclosed an electrically driven tuning fork provided with an adj usting device embodying the features of the invention.

Referring to the drawing, the fork 5 which is connected to a source of power such .as the grounded battery 6, is maintained in operatien by means of the electromagnet 7. One terminal of the operating electromagnet is grounded and the other terminal is connected to a contact spring 8 which cooperates with the fork tine 9 to provide a buzzer contact controlling the energization of the electromag-' net and consequently the vibration of the fork tines 9 and 10. A pair of contact s rings 11 f the tine 10 and alternately engaged thereby, serve to impress current impulses from battery 6, alternately on magnets 13, 13 and 14, 14, of a La Cour motor of the well known type which drives the synchronous mechanism at that station. 1

An electromagnet 15, the core of which is provided with pole faces 16, 16 of the same dimensions as the ends of the fork tines, is rigidly mounted on the base of the fork in the position as shown, the air gaps between the pole faces and the fork tines being made as small as possible without permitting the parts actually touching each other. The winding of electromagnet 15 is connected to a source of energy 17 in seriw with a variable resistance 18 and a current indicating 'device 19; When the fork'is set in vibration as by plucking, its operation is maintained by the intermittent current impulses flowing through electromagnet 7, and current impulses from battery 6 are thus transmitted to the operating magnets of the La Cour motor in the standard manner. The magnetic'eifect due to the'energization of electromagnet 15 serves to increase the apparent stiffness of the tines of the fork and thereby produce and in- 'justment easy tell the operating frequency at a glance.

The method of varying the frequency as described above, has been found superior to methods previously employed and is satisfactory under the rigid requirements of submarine cable operation. Not only is the adto make, but it can be accurately made while the fork is in vibration and then remains constant.

What is claimed is:

1. In a tuning -fork including a pair of vibrating tines, means for maintaining said fork in vibration, and electromagnetic means independent of said first named means cooperating with said tines magnetically to control their rate of vibration. 2. In a tuning fork including-a pair of vibrating tines, means for maintaining said fork in vibration, electromagnetic means independent of said first named means e0op erating with said. tines magnetically to control their rate of vibration, and means for controlling said electromagnetic means.

3. In a tuning fork including a pair of vibrating tines, means for maintaining said fork in vibration, electromagnetic means cooperating with said tines to control their rate of vibration, means for controlling said electromagnetic means, and means for indicating the frequency of vibration of said fork.

4. In a tuning fork including a pair of vibrating tines, means for maintaining said fork in vibration, and electromagnetic means cooperating with said tines magnetically to control their rate of vibration, said electromagnetic nieans including a core having its pole faces in operative relation with said fork tines and acting to increase the natural period of vibration of the fork.

5. In a tuning fork including a pair of vibrating tines, means for maintaining said fork in vibration, and electromagnetic means cooperating with said tines to control their rate of vibration, said electromagnetic means including a core having its pole faces in alignment with and in closerelation to the free ends of said fork tines.

6. In a tuning fork including a pair of vibrating tines, means for maintaining said fork in vibration, and electromagnetic means cooperating with said tines to control their rate of vibration, saidelectromagnetic means including a core having .a pair of pole faces substantially equal to Y in dimension and mounted closely in engagement with the free ends of said fork tines.v

7. The method of varying the frequency of a vibrating member which consists in sub jecting said member to a constant magnetic force. l

8. The method of varying the frequency of an electrically driven tuning fork including a pair of vibrating tines, which method consists in including said fork tines as a portion of a magnetic circuit and subjecting said magnetic circuit to a constant flux.

9. The method of adjusting the period of vibration of a constantly driven tuning fork having magnetic material in the tines, without bringing the tines to rest, which comprises setting up a magnetic field of the requisite strength in said magnetic material, said magnetic field tending to increase the frequency of vibration of said fork.

10. The method of adjusting the frequency.

of vibration of a constantly driven vibrating element eomprisin magnetic material, without bringing the eIe prises varying the strength of a magnetic field in which the magnetic material vibrates, said magnetic field tending to increase the frequency of vibration of the vibrating element.

11. A vibrating system comprising a vibrating element having a vibratory magnetic portion, driving means therefor, in combination with frequency control means independent of said driving means, comprising a magnetic stationary element and means for setting up a substantially continuous magnetic flux in a magnetic circuit including said vibratory magnetic portion and at least a portion of said stationary element.

In witness whereof, I hereunto subscribe my name this 26 'day of December, A. D. 1923.

ALLISON A. CLOKEY.

ment to rest, which com- 

